The transmission system operators (TSOs) started working on the principles of a common platform back in 2016, with the goal of meeting a 2022 start-date set out by the European Commission.

The memorandum of understanding signed by the TSOs sets out guiding principles for the successful implementation of the project. They will cooperate on the design, implementation and operation of the initiative whilst consulting with various stakeholders including national regulators.

The European Commission is currently in the process of introducing regulation to establish guidelines for the cross-border trading of balancing services. The guidelines foresee the introduction of platforms to facilitate the exchange of all types of balancing services and not just frequency response.

According to the draft regulation, its aims include fostering "effective competition, non-discrimination and transparency" in balancing markets; enhancing their efficiency at both the European and national level; "promoting the possibilities for exchanges of balancing services while contributing to operational security"; and enabling electricity grids to absorb a growing volume of renewable generation.

When asked how its involvement in the new balancing initiative would be affected by Britain's departure from the EU, a National Grid spokeswoman said: "National Grid is working closely with stakeholders to understand the implications of Brexit, and we can continue to be committed to working alongside our European partners on projects like MARI."

However, he also warned that keeping Britain's regulations aligned with those of the internal energy market post-Brexit would leave the UK as a "pure rule-taker" and that energy policy risked being caught up in the wider Brexit negotiations.